speech to text conversation through API

can anybody 开发者_如何学Csuggest API either free (that's very good) or paid to convert speech in to text for iPhone application.

Thanks, AAryan

At one point I was going to look at trying to port this library to the iPhone:

http://www.speech.cs.cmu.edu/sphinx/tutorial.html

It has the capability to build your own speech dictionaries.